Filter manufacture



Aug- 18, 1953 F. w.vMAURER ET AL 2,649,395

FILTER MANUFACTURE Original Filed Dec. 30, 1946 30000 nunon 000D auun a00a annum IN VEN TORS ATTORNEYS' Patented Aug. 18, 1953 UNITED STATESPATENT OFFICE FILTER MANUFACTURE Frank W. Maurer, Newton Highlands, andJack B. Hirschmann, Fairhaven, Mass., assignors, by mesne assignments,to Jack B. Hirschmann 3 Claims. (Cl. 154-125) This invention relates toa filter particularly adapted for uses such as in a goggle or similardevice to lter and diffuse the air or other gas entering the eye chamberor other enclosure.

One of the principal objects of the invention is to provide such afilter which is simple and inexpensive to produce and which is soconstructed that it may be quickly and easily removed or replacedwhenever desired, as for example when it becomes clogged with dust orother foreign matter.

Another object is to provide such a lter which includes a layer offilter material secured to a perforated and flexible supporting memberof suiiicient stiifness to permit ready handling and ready attachment inposition for use without injury either to the lter itself or to thegoggle or other device wherewith it is used.

It is also an object of the invention to provide such a lter which canbe readily and cheaply produced in quantity with the cloth or otherfilter material bonded to the supporting member to form a complete unitready for attachment in position for use and which is formed forcooperation with attaching members permanently mounted on the goggle orother device wherewith the lter is to be used.

A further object is to provide a method of producing a iilter of theabove characteristics which is simple and inexpensive and which isparticularly adapted for mass production of such filters at low unitcost.

Other objects and advantages of the invention will be apparent from thefollowing description, the accompanying drawing and the appended claims.

In the drawing, in which like characters of reference designate likeparts throughout- Fig. 1 is a view in front elevation illustrating alter constructed in accordance with the invention and mounted in agoggle, the view being partly broken away substantially on the centerline of the filter to illustrate details of internal construction;

Fig. 2 is a View in vertical section taken on the line 2--2 of Fig. 1and with portions of the goggle broken away for greater clarity;

Fig. 3 is a detail View in elevation of one side of a lter unitconstructed in accordance with the invention;

Fig. 4 is an elevational View of the opposite side of the filter unitshown in Fig. 3;

Fig. 5 is an enlarged fragmentary sectional view taken substantially onthe line 5 5 of Fig. 3;

Figs. 6, 7 and 8 are somewhat diagrammatic views in perspectiveillustrating steps in the production of the filter unit shown in Figs.3-5;

Fig. 9 is a view similar to Fig. 3 showing another lter unit constructedin accordance with the invention;

Fig. 10 is an enlarged sectional view taken on the line I U--I 0 of Fig.9; and

Fig. 11 is a view similar to Fig. 9 showing still another lter unitconstructed in accordance with the invention.

The present invention provides :dlters for ventilation purposes whichcan be used until they become clogged or otherwise ineffective and canthen be quickly replaced with a fresh filter. These filters areaccordingly of such characteristics that they can be made Very readilyin quantity at low unit cost and hence can be economically thrown awayafter they become ineiective. The invention provides such lters ascomplete units, including both a layer of filter material such as clothand a supporting member of sufcient combined rigidity and resiliency tosupport the filter material in efdcient filtering relation with the portor ports with which it is used. This supporting member and the filtermaterial are secured together, and the supporting member includes meansby which the combined unit may be mounted directly in position for usewith the supporting member thus serving as a part of the mounting meansfor the lter unit. In some embodiments of the invention, the l'iltermaterial and supporting member are permanently secured together and inother such embodiments the lter material is readily removable from thesupporting member to permit its replacement by fresh lter material. Ineither case, the filters of the invention are well adapted for useswhere periodic replacement is necessary, as for example in such devicesas goggles, masks, respirators or the like.

Referring to the drawing, which illustrates preferred embodiments of thepresent invention, Figs. l and 2 show iilters constructed in accordancewith the invention and mounted for use in a goggle comprising aone-piece rubber frame which includes a rim portion IU adapted torearound a considerable portion of the peripheryy of the frame to serveas ventilation ports as( illustrated in Figs. l and 2, these openings orports l being shown as generallyretangular. inoutline. The presentinvention nis. ofncerefd with the provision of a filter which can beused t0. prevent the entry of dust particles or like foreign matter intothe eye chamber .thro ghthel ventilation ports while at thesanieftimepermitt' :s adequate liow of air or other gas therethrou hf; J

the plas `c under stress tending to urge it outfor proper ventilation ofthe eye chamber: '1-so;

the invention is directed to the provision-ofsuch a lilter which can besimply and easily replaced when it becomes clogged`with dust orotherwise inemcient, and wl'iifclifc therefore be produced cheaply andthrown awaysafvter use.

Figs.. '3;5' illustrate i`n `detail a lil-ter constructed in accordancewith the invention and fulfilling the above'rquirements, and Figs.A land 2V illustrate the mounting'of suol-ia lter in the goggle. Asshownfthisiilterincludesan elongated and somewhat'crescent-shaped`stripof exible material 'ofsuch' form astont` within the goggle frame and tooverlie the inner surface of the frame portion I2, as s l-iownyi-n'ig's.71 and 2. I'his strip 2lil in turn has 'a'layer'z of i'ilter materialsuoli as cloth overlying 'onesurface 'thereof` and adhered thereto toform a complete unit., Satisffactory results, have been obtainedutilizing cellulosefacetateffor the Hitler-supportingmember 2l), thismaterial haifingv adequate stilness in' relatively thin layers `to`holdits shape but at the saine time beingfsuiici'ently flexible topermit ready deformationfrf'prop'er tvwithin goggle HThelayer-22 ofVlter material may compri any cloth of silicient thickness and Sufi'-ciently close fwea've lt'retainl undesired particles of'dst or the likewhile stlllperinitting ready passage of air therethrough, satisfactoryrnateria'l for`thi`s`purpse being cloth or the type of'a'felt rfla'nneli'A Asshown inthe drawing, the :filter-support'- ing member 2G isforin'edwith a multiplicityof spaced apertures therethrough 'for the same numberand `(relative spaoingfasfthe ports I5 in the goggle; frame portion'IZ',but the cloth layer 22. com'pletely'verli'esoneV surface rof thissupporting member'E exceptfor vthe mounting holes 32A and'ff, andtherebyfse'rves to filter air or gas traversingthe apertures '25. Withthis construction/when the lter'u'nit `is mounted within-the goggleinthe mannerY shown in Figs. l and`2, the cloth layer 22Y lwill be heldbetween the plastic layerY 2li and theinner surface of theframe portionVl2, and with theapertures 25 in the plastic layer iny properlyregistering relationl With` the `ports |752 in theffrayrne, the cloth22, will thus filter all air or other'gasxentering theA eyechamber asclearly shown in Fig.. 1. Y

1 and 2'Y also illustrate means for removably lsecuringA the :filterunit in position within the g` og `g le. V 'v s the frame, portion I2has, a number of'prnale: fasteningmembers or studs 3l)y mounteduthereinand 'projecting inwardly. VFor 4; example, these members 30 may comprisemale fastener members of the well known dot type. The lter unit is inturn provided with holes punched completely through both the plastic andthe cloth to cooperate with these male fasteners. As shown, there arethree such fasteners at each side of the goggle, and each filter unit isaccordingly provided with three holes to coopcrate4 with the.`fasteners,` vthe, two linoles.- 32 at either end 01E, the llterbeinglsubstantially circular but the intermediate hole 33 being a slotextending generally parallel to the length of the iilter.

"'With this construction, when the lter is mounted in a goggle as shownin Figs, 1 and 2, the holes ,32 andkprovide the female portions of theftunits; rand the studs 30 snap into these ho; (insecure the filter inplace. The studs St in theue'ridlholes 32 anchor the iilter inpositicrnv and s'nce; the plastic layer 20 is bowed tJo conform with thecurve of these end connections retain o ioni, II

wardlyl'and thereby to press the iilter layer 22 lirmly against theframe to prevent leakage of dustvaround the filter.` At the same time,the slot'- permits relative adj listingmoveifnent betweentllieplastio-layer 22l and the frame in use, particularly such adjustingasis necessary flor comfortable lit off/the goggle on the Vraceofthe.-wearer. When itv is desired to removeor replace the filter, this maybeV-'donefquiollyand veasilyfbyY simply unsnapping thev'iasterierv studsfrom holes and iBS-,j andl a new lter-:maybe mounted position with equalease.

The 'nl-ter units ofthe 'present invention are, readily made by massproduction methods at low unit cost, and; Figs. GLSA Villustratestepsinthe 1nethodofproducing these'lilters.` Referring tcl Fig. 6, adquantity ofiilters may beniadesimule tancously starting; with a sheetit` of suit-able material' ffor the 'supporting layer ofthe, filter.This sheet may comprise any Vof a varietyoi"i materials of adequate4v stiin'ess rvand resiliency in layers suiciently thin fo'r-,usefasdescribed, suitable materialsrincluding plastics such as cebluloseacetate or other cellulose esters, orthinsheets off spring metal.''ili'c first lstep in `the methodA ofthe inventionis-to cut'outfin sheet#lil a plurality ofagroupsA ofapertures '-arrangedg andsp'acing Yof theyventilation ports with which they are toI register in usefwh'ieh-canfreadily be done lby'asimple"die-cutting operation, with all theapertureysl 21.5- for'A allV theVv filter unitsto be formed fromthe'same vsheet ielbeing cut; at-t'he same time, as shown in Fiati; m

In the next step ofy themethodyxagsheet 'llgor thef 'rediclotliorf-other lter-mlaterial'is superimpeV ed? on onefsurface-or-t-heplas-tic sheet, asY showni'n Figi 7, 'andcausedtowadhere'to the plastic.This may bedQIlei/ery readily by applyingr'to` the w V"l a' '21 coatingolfhadhesive material and Y v Y Lrlyingtheeloth 'layer tliereto.vnForexample, inthe-'case of cellulose acetate, theadhesivemayffcxoinprise 'a *solution of-celluloseacetate in asolventsuchas acetone oramixture of acetone and"methyl"Cellosolve,y l-fauchan',- adhesive, in a relatively iluidcondition,VV applied tothe,Sheet. it .witaabrgsh-01 lillerrit wiigai' thev selig.' arasjtge.'Sheet/"btt leave the, nierturs worse. S9 ,111i flieg the (219th layeris suseriglrqsed. @Sheer it Willibe. beaded.. t0 the 'Selig ereasggfihegsliset but. there 'l bano. effect on 'the portions of the 'clothoverl g *beseL apertures 25, which will remain clear for the propertransmission of gas therethrough. The final step of this method is tocut out the individual lter units 50 from the composite sheet 411-42, asshown in Fig. v8. This also may be done by a simple die-cuttingoperation, and the die may also be formed to cut the holes 32 and slots33 in the units at the same time.

Fig. 7 also illustrates another method of carrying out the adhesionbetween layers 40 and 42, which can be carried out when its supportinglayer l0 is a plastic. With the filter layer 42 superimposed on layert0, a volatile solvent for the plastic is applied to the filter layer,as indicated at 45 in Fig. 7, a suitable solvent being acetone in thecase of cellulose acetate. The solvent will penetrate the filter layer42 and soften the adjacent surface of the plastic layer suiciently tocause an intimate bonding between the two layers, no pressure beingrequired during this operation other than the mere weight of the filterlayer itself. Then when the solvent has evaporated, which takes placerapidly, the two layers will be formed to be intimately bonded together.

Figs. 9 and 10 illustrate a filter unit similar to that shown in Figs.3-5 but of somewhat different construction. In this filter, thesupporting member Si) is substantially the same as member 20 in Figs. 35, but the lter material `B2 is in the form of a tube of suitable clothinto which the member 66 is inserted. This tube 62 may be ofsubstantially the same length as member 60, in which case it can haveholes therethrough to match the mounting holes B5 in member 60, or itcan be of sufficiently lesser length, as shown, to leave exposed theends of member 60 and the holes t5. Similarly the tube 62 may have slotsii cut therethrough matching the corresponding slot in member 53, or itmay be made in two parts as in the lter shown in Fig. ll.

Referring to Fig. l1, in this lter the supporting member 'l0 is formedof wire, bent to approximately the same outline as members 20 and 60 andincluding loops 'H and 'l2 which form the female mounting members. Thefilter material is formed of two tubes 'l5 each suiiiciently less thanhalf as long as member 10 to leave exposed the loops 'll and l2, one ofthese tubes being removed in Fig. 11 to show the form of member i0.Member 'it may also be formed, as shown, with barbs 'il adapted to catchon the filter tubes and thus aid in securing them to member 1D. Witheither of the filters shown in Figs. 9-11, when the lter materialbecomes clogged or otherwise ineffective, the unit may be snapped out ofplace and the tube or tubes removed from the supporting member andreplaced by a fresh tube or tubes. This operation can be carried outsubstantially as quickly as the replacement of the filters shown inFigs. 3-5 and has the advantage that the supporting members can bereused, thus further reducing expense.

It will accordingly be seen that the present invention provides lterswhich are eiiicient in use as well as simple to install or replace. Theinvention also provides a methodby which these filters may be rapidlyand easily made from relatively inexpensive material, and even utilizingsuccessfully materials which would otherwise be suitable only for scrap.For example, in the formation of cellulose acetate sheeting by theconventional baby cake method, the two or three sheets formed from thematerial adjacent the outer surface of the cake usually have a somewhatfrosted appearance and hence are unsuitable for optical usefonotheru's'es wherein trans"- parency is desired. However, such frosted sheetsare perfectly satisfactory for the purposes of the present invention. y

Since the ltersof the invention can thus be produced at low unit cost,it is practical to use them only once and then to replace and discardthem after they have become clogged or. otherwise lost theirefficiency.' They are useful not only in goggles of the-type shown inthe drawing but also have particular application in gog- -gles of thetype shown in Patent No. 2,387,522, assigned to Athe. same assignee'asthis application, wherein the gas inhaled 'by the wearer passes throughthe eye chamber to prevent fogging of the lens. They may also be usedsuccessfully as ventilation iilters for other devices such, for exampleas masks and respirators, such use requiring only proper shape andarrangement of the holes in accordance with the particular design of thedevice Wherewith the filters are to be used.

This application is a division of our application Serial No. 719,326filed December 30, 1946, now Patent No. 2,573,722 issued November 6,1951.

While the method herein described constitutes a preferred embodiment ofthe invention, it is to be understood that the invention is not limitedto this precise method, and that changes may be made therein withoutdeparting from the scope of the invention which is defined in theappended claims.

What is claimed is:

1. In a method of producing a lter of the character described includinga layer of filter material and a perforate flexible supporting memberfor said lter material, the steps of forming in a sheet of organicplastic material a plurality of apertures, superimposing 1a lter clothon one surface of said apertured plastic sheet, and saturating saidcloth with a volatile solvent for said plastic While said cloth and saidplastic sheet are in intimate contact to soften the surface of saidplastic sheet adjacent said cloth with resultant intimate bondingbetween the adjacent surfaces of said sheet and said cloth whilemaintaining the areas of said cloth overlying said apertures free ofsaid plastic for proper transmission of gas therethrough.

2. In a method of producing multiple filters of the character describedeach including a layer of lter material and a perforate exiblesupporting member for said filter material, the steps of forming in asheet of organic plastic material a series of groups of apertures,superimposing a lter cloth on one surface of said apertured plasticsheet, saturating said cloth with a volatile solvent for said plasticWhile said cloth and said plastic sheet are in intimate contact tosoften the surface of said plastic sheet adjacent said cloth withresultant intimate bonding between the yadjacent surfaces of said sheetand said cloth while maintaining the areas of said cloth overlying saidapertures free of said plastic for proper transmission of gastherethrough, and then cutting the resulting composite sheet of clothand plastic into individual lter 3. In a method of producing multiplelters of the character described for use in an enclosure having maleattaching members for supporting the lter in position to filter anddiffuse gases entering said enclosure, the steps of forming in a sheetof organic plastic material a series of groups of apertures, applying toone surface of said apertured plastic sheet a filter soften? anda to;adhr intimately '17e-*the adaeent feet. on 'th'ef areas ot?saiii"o10th=. overly-ing said' apertuteslanduherebyle'avingfsaid'apertures tree of said plastic:- for.` propel?ransmissiojn o'f g therethrough; and` thexeaitercuttingfthe uesuiif ingcomposite, swofitiloth mdiplalstc; n't'o infeach suhtlter'unit through.both said cloth and said plasticsheet for cooperationY with said maleattaching members.

JACK B. HIRSCHMANN.

Reeences' Cited in the le of this patent UNITED STATES PATENTS NumberName Datel 10v 1,970,755 Knoll Aug. 21, 1934'v 1,999,283 Clemens Apr.3D, 1935 2,389,435

dividual; lter unitaadf alsof forming: holes: in'.

Karlstrom Nov. 20, 1'945

1. IN A METHOD OF PRODUCING A FILTER OF THE CHARACTER DESCRIBEDINCLUDING A LAYER OF FILTER MATERIAL AND A PERFORATE FLEXIBLE SUPPORTINGMEMBER FOR SAID FILTER MATERIAL, THE STEPS OF FORMING IN A SHEET OFORGANIC PLASTIC MATERIAL A PLURALITY OF APERTURES, SUPERIMPOSING AFILTER CLOTH ON ONE SURFACE OF SAID APERTURED PLASTIC SHEET, ANDSATURATING SAID CLOTH WITH A VOLATILE SOLVENT FOR SAID PLASTIC WHILESAID CLOTH AND SAID PLASTIC SHEET ARE IN INTIMATE CONTACT TO SOFTEN THESURFACE OF SAID PLASTIC SHEET ADJACENT SAID CLOTH WITH RESULTANTINTIMATE BONDING BETWEEN THE ADJACENT SURFACES OF SAID SHEET AND SAIDCLOTH WHILE MAINTAINING THE AREAS OF SAID CLOTH OVERLYING SAID APERTURESFREE OF SAID PLASTIC FOR PROPER TRANSMISSION OF GAS THERETHROUGH.